Preparation of polysaccharide beads

Abstract

The present invention relates a method of preparing agarose beads, which method results in a population of beads which are of relatively uniform particle size. In an advantageous embodiment, the beads are of a particle size less than 10 μm, and the coefficient of variation C.V. of the population is less than 15%. The beads according to the invention are advantageously used in biological separation methods, such as in the production of chromatographic packing materials; drug carriers; or in any method of biological engineering.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a filing under 35 U.S.C. §371 and claims priority to international patent application number PCT / SE2008 / 000283 filed Apr. 21, 2008, published on Nov. 6, 2008, as WO 2008 / 133571, which claims priority to patent application number 200710098700.9 filed in China on Apr. 25, 2007.FIELD OF THE INVENTION[0002]This invention relates to the preparation of polysaccharide particles, such as agarose beads, for use in biological separation, such as the purification of proteins and / or cells, as drug carriers or in general in the field of biological engineering.BACKGROUND OF THE INVENTION[0003]Agarose is a natural polysaccharide extracted from algae, and its aqueous solution forms a hydrogel at low temperatures. Agarose has been used as chromatography medium since 1960s, and has many advantageous characteristics, such as high hydrophilicity, high porosity, and hydroxyl groups available for functionalization. Agarose is frequently use...

AI Technical Summary

Benefits of technology

The present invention is about a method for making agarose gel beads with small particle size and a high agarose content. The method avoids the drawbacks of previous methods. The resulting beads have an average particle size of less than 10 μm and a uniform particle size. The agarose content of the beads is as high as 20 wt % (by total bead weight). This invention provides a population of agarose gel beads with small particle size and a high agarose content.

Problems solved by technology

However, known drawbacks of such emulsion methods are that the particle size of the liquid droplets can not be controlled, the prepared emulsion has uneven particle size, the cured agarose gel beads have uneven particle size.

Uneven particle size will lead to complex characterization of beads.

In addition, it is very difficult to control the particle size of the prepared beads and to prepare beads of small sizes such as below about 10 μm in these traditional preparation processes.

The traditional membrane emulsification can result in particles of even size.

An increased pressure can increase the emulsification rate to a certain extent, but too high pressure was shown to reduce the particle size uniformity of beads.

When beads have high agarose content, high pressure leads to severe broadening of the bead size distribution.

This is considered a substantial drawback of this traditional method for certain applications, where both high agarose content and a small particle size are important.

Thus, some problems are known with the agarose medium widely used in biological separation field.

This gel formed by non-covalent structure has low mechanical strength, and is consequently not capable of withstanding very high flow rates.

In case of use of traditional membrane emulsification method to prepare agarose gel bead, the increasing viscosity of water phase brings about difficulties in emulsion preparation process.

It is very difficult for the formed liquid droplets to detach from the membrane surface due to the higher viscosity of the water phase.

The experiment results show that when traditional microporous membrane emulsification method is used to prepare gel beads with small particle size and high agarose content, high viscosity of the water phase leads to slow W / O emulsion preparation process even at high pressure.

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